Breast Infection

Breast Infection Overview

Mastitis is an infection of the tissue of the breast that occurs most frequently during the time of breastfeeding. This infection causes pain, swelling, redness, and increased temperature of the breast. It can occur when bacteria, often from the baby's mouth, enter a milk duct through a crack in the nipple. This causes an infection and painful inflammation of the breast.

Breast infections most commonly occur 1-3 months after the delivery of a baby, but they can occur in women who have not recently delivered as well as in women after menopause. Other causes of infection include chronic mastitis and a rare form of cancer called inflammatory carcinoma.

• The breast is composed of several glands and ducts that lead to the nipple and the surrounding colored area called the areola. The milk-carrying ducts extend from the nipple into the underlying breast tissue like the spokes of a wheel. Under the areola are lactiferous ducts. These fill with milk during lactation after a woman has a baby. When a girl reaches puberty, changing hormones cause the ducts to grow and cause fat deposits in the breast tissue to increase. The glands that produce milk (mammary glands) that are connected to the surface of the breast by the lactiferous ducts may extend to the armpit area (axilla).
• A breast infection that leads to an abscess is more serious. If left untreated, an abscess, which is an infection within an enclosed space that forms a collection of pus, can develop in the breast tissue. This type of infection may require surgical drainage.

Breast Infection Causes

Mastitis (inflammation of breast tissue) is a common benign cause of a breast mass. It is commonly seen in women after childbirth while breastfeeding. These masses are often quite painful. Women who are not breastfeeding can also develop mastitis. In healthy women, mastitis is rare. However, women with diabetes, chronic illness, AIDS, or an impaired immune system may be more susceptible.

• Bacteria normally found in a baby's mouth or on the nipple can enter the milk ducts through small cracks in the skin of the nipple and can multiply rapidly in the breast milk. This can lead to a superficial small area of inflammation (frequently from a streptococcal germ) or a deeper walled-off infection or abscess (frequently from a staphylococcal germ).
• Mild temperature elevations (previously termed milk fever) accompanied by some breast or nipple soreness is usually secondary to engorgement and dehydration immediately (48-72 hours) after delivery and is treated by improved breastfeeding technique. This condition may also occur in women who are not breastfeeding and have not completely suppressed lactation yet.
• About 1-3% of breastfeeding mothers develop mastitis, usually within the first few weeks after delivery. Most breast infections occur within the first or second month after delivery or at the time of weaning. Engorgement and incomplete breast emptying can contribute to the problem and make the symptoms worse.
• Chronic mastitis occurs in women who are not breastfeeding. In postmenopausal women, breast infections may be associated with chronic inflammation of the ducts below the nipple. Hormonal changes in the body cause the milk ducts to become clogged with dead skin cells and debris. These clogged ducts make the breast more open to bacterial infection. Infection tends to come back after treatment with antibiotics.